Impact fuze

ABSTRACT

1. In a missile the combination comprising: A. A HOLLOW METALLIC NOSE SECTION AND A HOLLOW METALLIC TAIL SECTION, SAID SECTIONS BEING CONCENTRIC ABOUT THE LONGITUDINAL AXIS OF THE MISSILE FOR STORING ELECTROSTATIC ENERGY GENERATED BY THE PASSAGE OF THE MISSILE THROUGH THE ATMOSPHERE; B. A DIELECTRIC SECTION SEPARATING AND ELECTRICALLY INSULATING SAID NOSE AND TAIL SECTIONS ONE FROM ANOTHER; C. OPPOSITELY DISPOSED FIRST AND SECOND ELECTRICALLY CONDUCTIVE PLATES ELECTRICALLY INSULATED ONE FROM ANOTHER AND ELECTRICALLY CONNECTED TO RESPECTIVELY SAID NOSE SECTION AND SAID TAIL SECTION; AND D. A SUBSTANTIALLY NONINDUCTIVE ELECTRICAL DETONATOR CIRCUIT CAPABLE OF WITHSTANDING VOLTAGES OF ABOUT 5,000 VOLTS INCLUDING ELECTRICALLY ACTIVATED DETONATING MEANS CONNECTED BETWEEN SAID FIRST AND SECOND PLATES WHEREBY SAID NOSE SECTION FIRST MAKING ELECTRICAL CONNECTION WITH A TARGET AT IMPACT DISCHARGES ITS ASSOCIATED CHARGE TO THE TARGET AND A POTENTIAL DIFFERENCE IS THEREBY ESTABLISHED ACROSS SAID DETONATOR CIRCUIT.

Einite States atent Hovnanian Sept. 9, 1975 1 1 IMPACT FUZE Primary ExaminerRobert F. Stahl [75] Inventor: Hrair Philip Hovnanian, Assistant bxammer' Jordan Windlestera Mass Attorney, Agent, or F1rmM. E. Frederlck 73 As ee: Avco C0 0 ation, Ci cinnati, Ohio I 1 5 rp r n EXEMPLARY CLAIM [22] Filed: Feb. 25, 1959 1. In a m1ss11e the comb1nat1on compr1s1ng: [21] App1.No.: 795,506 a. a hollow metallic nose section and a hollow metallic tail section, said sections being [52] Us Cl 102/702R concentric about the longitudinal axis of the "F42C 1.1/00 missile for storing electrostatic energy generated 58 Field of Search 310/6, 7; 102/702, 70.2 G, by the passage of the M5511? through 102/56 92.5 atmosphere;

b. a dielectric section separating and electrically [56] References Cited insulating said nose and tail sections one from another; UNITED STATES PATENTS c. oppositely disposed first and second electrically 5 9 4/1950 Goufdon 102/701 conductive plates electrically insulated one from 3179 l 963 5/1957 f ct 102/702 another and electrically connected to respectively 2 22: 1 said nose section and said tail section; and $2 3 6119s) 102/702 (:1. a substantially noninductive electrical detonator 925 776 2/1900 Fcrrism: IIIIIIIIII: 102 7022 circuit capable of withstanding voltages of about 5' H1961 Bcrgva. 102/701 5,000 volts including electrically activated 2:99(),775 7/1961 l-lcnson 102 914 detonating means connected between said first 2,997,955 8/1961 Wade ct a1 .1 102/924 and second plates whereby said nose section first FOREIGN PATENTS OR APPLICATIONS making electrical connection with a target at impact discharges its associated charge to the 91,592 2/1938 Sweden 102/702 P target and a potential difference is thereby established across said detonator circuit.

I 1 I I 3 Claims, 2 Drawing Figures 5 7\ $1 I p/ 0/ 3 h Q 40 2/4; j 8 I 1 6 1O 4 PATENTED 9|97'5 3, 9939805 HRAIR PHILIP HOVNANIAN INVENTOR.

ATTORNEYS IMPACT FUZE The present invention relates to fuzes for explosive missiles. More specifically, the invention relates to an impact fuze for detonating an explosive missile upon impact with a target, whether it be a ground target or an aerial target.

Although not limited to such use, the present invention is particularly well adapted to intermediate range and intercontinental missiles. A characteristic of such devices is the relatively high speed at impact. This necessitates an extremely fast-acting fuze to assure detonation before crushingof the missile. At present, piezoelectric devices are being used with some degree of success to generate signals for triggering the fuzing systern. Unfortunately, such fuzing systems are relatively slowacting, necessitating mounting of the warhead at a point relatively remote from the nose of the missile to prevent mechanical destruction prior to detonation. Such a requirement affects the entire design of the missle, both aerodynamically and structurally and, introduces a factor of unreliability that is highly objectionable. Further, some physical deformation of the piezoelectric element is required to generate the trigger signal.

Piezoelectric signal generators are also objectionable in being too sensitive to spurious effects that are capable of prematurely detonating the warhead. Being pressure-sensitive devices, the fuze system may be triggered by extraneous blows other than impact. This presents a problem from the standpoint of handling such devices and makes them susceptible to countermeasures generating shock waves in the region of the missile prior to impact.

Another objection to conventional fuzing systems is their relative complexity. The large and complicated nature of electrical components employed in such a system makes for unreliability. Such systems also require a special source of electrical energy.

In contrast, the fuzing system of the present invention is fast-acting, highly reliable, and insensitive to forces other than those occurring at impact with the target. The invention is structurally simple and employs few components, none of which is complex or sensitive to mechanical shock or to radiant energy such as cosmic rays. In contrast, components, such as thyratrons, used in conventional fuzing systems must be elaborately shielded to preclude changes in operating characteristics under the influence of cosmic rays encountered at high altitudes.

Being a relatively insensitive device, the present invention is relatively shock resistant and provides a maximum of safety to personnel handling such devices.

Briefly, the present invention comprises means for storing electrostatic charges generated on the surface of the missile by its high velocity passage through the atmosphere. The charges are stored on the plates of a capacitor that are separated by a dielectric and interconnected by an impedance associated with the detonator of the warhead. Upon impact, the charge accumulated on one plate of the condenser is discharged to ground, establishing a potential difference across the impedance of the detonator. Flow of current under the influence of the potential difference triggers the detonator which in turn sets off the warhead carried by the missile.

From the foregoing it will be understood that a broad object of the present invention is to provide an improved fuze.

Another object of the invention is the provision of a fuze that is simple, reliable, fast-acting, and insensitive to extraneous effects.

A further object of the invention is the provision of a fuze that is insensitive to cosmic rays and to countermeasures.

A still further object of the invention is the provision of a fuze that does not require a separate source of electrical energy but instead, develops its own source during passage through the atmosphere.

Other objects of the invention are the provision of:

a. A fuze that may be used equally well with a missile having either metallic or nonmetallic components b. A fuze that does not impose critical impact requirements on the missile c. A fuze that does not require electrical shielding d. A fuze that may be stored for long periods of time without deterioration e. A fuze that is always ready for immediate use f. A fuze utilizing components and techniques that are well within the existing state of the art The novel features that I consider characteristic of my invention are set forth in the appended claims; the invention itself, however, both as to its organization and method of operation, together with additional objects and advantages thereof; will best be understood from the following description of specific embodiments when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic longitudinal sectional view showing the novel fuze associated with a missile having electrically conductive wall portions; and

FIG. 2 is a similar view taken through a missile having electrically nonconductive wall portions.

An inherent limitation of fuzing systems employing electrical current is the need for a source of electrical energy. Numerous prior art devices have been devised for producing the necessary electrical energy. Such devices are usually very elaborate and may employ inertial generators or batteries.

In contrast, the present invention does not require such devices. Energy for operating the fuze system is derived from the static charge accumulated on the missile during its passage through the atmosphere. It is well known that a high velocity missile may develop a static potential of many thousands of volts due to the electrostatic phenomenon of air particles rubbing over the surface of the missile. By conservative estimate, a potential of 5000 volts may be established in this manner, and sufficient energy may be stored to trigger even relatively insensitive detonators requiring relatively large current discharge for energiZatio-n.

For purposes of illustration, there is shown in FIG. 1 a simplified sectional view through an intercontinental ballistic missile having a nose section 1 and a tail section 2. Between the nose and tail sections is imposed a dielectric 3 preventing direct discharge between capacitor plates 4 and 5. Plate 4 is electrically connected to nose 1 whereas plate 5 is connected to the tail section 2.

Connected between plates 4 and 5, as by conductors 6 and 7, is an impedance 8. The impedance may take the form of a simple bare wire resistor with which is associated ignition bead 9 of detonator 10. The detonator itself is associated with warhead 11 in conventional manner.

As will be understood by those skilled in the art, the ignition bead 9 may be triggered by heat. Such heat may be developed by discharge of electrical energy through the resistor. Assuming for purposes of illustration, but not by way of limitation, an ignition bead made from trinitroresorcinate [C H (N09,, (O Pb)l, triggering may be effected by heating the ignition bead to a temperature of 590F.

At the time of launching, all portions of the missile are at a common potential, normally ground potential. During flight through the atmosphere both nose and tail sections accumulate a substantial electrical charge as has been explained. Upon impact, the charge accumulated on the nose section is discharged to ground potential, or other potential of the target, practically instantaneously. Since the charge on the tail section has not been dissipated, a potential difference is established across resistor 8. The ensuing flow of current rapidly heats the resistor and the ignition bead, triggering the detonator, in a matter of a few hundredths of a microsecond after the time of initial impact.

Since it is merely necessary that the charge on the nose section flow to ground, the angle of impact of the missile is not critical. Any impact discharging the nose section, but not the tail section, is sufficient. This is obviously a substantial advantage in minimizing critical limitations affecting the design of the missile.

By way of illustration, characteristic dimensions may be assumed to demonstrate the operation of the fuze. Assuming diameter d equal to 16 inches, thickness 11 of the dielectric equal to 2 inches, and a dielectric constant ;1. equal to 10, the capacitance of the plates 4 and g 5 may be readily approximated by the following formula:

C: 477/1 47Th (I) 200 uaf where: A area of plate 45 Resistor 8 may have a value of about 100 ohms giving an RC time constant equal to .02 microseconds.

By conservative estimate, the missile will charge to a potential of 5000 volts during flight. It follows, there-.

fore, that upon impact, after the nose section has discharged to ground potential, a 5000 volt potential difference will exist across the resistor, and all of the energy stored by capacitor plates 4 and 5 will be available for heating the resistor and its associated ignition bead.

Based on the foregoing assumed values, the energy stored by the capacitor plates at time of impact is as follows:

2.5 X 10 joules 2.5 X 10 ergs where:

W energy C capacitance in farads E potential of capacitor in volts An energy source of 25,000 ergs is more than sufficient to trigger conventional detonators. In order to avoid over-sensitivity, such detonators may be designed to require energy sources as high as 20,000 ergs. It is readily obvious that enough energy is available even to trigger such devices.

Since long-time electrical storage devices, such as batteries, are not necessary, storage of missiles for long periods is possible without servicing. Further, since no deterioration occurs, missiles having the novel fuze are always ready for immediate firing.

From the foregoing description, it will be evident that the fuze system is not sensitive to mechanical shock, as would be the case if a piezoelectric signal generator were employed. Further, no potential difference exists across the impedance of the detonator until the missile is in flight. These are obviously important safety factors for personnel handling such missiles.

Further, a detonator may be utilized that requires a relatively large energy source, making it relatively insensitive to minor electrical effects such as created by countermeasures. In other words, a missile equipped with the present invention can pass through large ionic fields without premature detonation. In addition, since none of the components of the system depends upon ionization, as is sometimes required by thyratrons in conventional systems, the fuze is insensitive to cosmic radiation and no shielding is required.

In view of the relatively short RC time constant, the fuze is extremely fast-acting, so much so that it is not necessary to locate the warhead towards the rear of the missile to prevent mechanical destruction before detonation.

An advantage of the present invention is that the fuze may be readily used in conjunction with other types of fuzing systems. This is possible because of the simple, light-weight nature of the present device making it readily adaptable to other systems. In this way, substantially reliability can be assured.

As an additional safety factor, a time-operated switch S can be inserted in conductor 6 or 7 to prevent arming of the missile until some predetermined time after launching.

An inherent time delay occurs before effective arming when the missile, assuming it to be an intercontinental ballistic missile, reenters the atmosphere. At such time, ionization of the atmosphere surrounding the missile occurs, providing an electrically conductive path by which the accumulated charge on the missile may be dissipated. Ionization terminates at a relatively high altitude, providing ample time for reaccumulation and arming of the missile prior to impact.

Obviously, a missile or projectile equipped with the present fuze may be used effectively with any target against which impact may occur. For instance, detona tion may occur as the missile strikes an airplane, the water, or the ground. In case impact occurs with a semiinfinite plane, such as the earth, the potential available for purposes of detonation is substantially doubled. This results from the finite approach of electrical charges on the missile toward equal and opposite image charges in the semi-infinite plane at the point of impact.

As shown in FIG. 1, the nose and tail sections of the missile are made from metal through which accumulated charges readily move to the capacitor plates 4 and 5. The intervening dielectric section may be made from quartz or any other material having sufficient dielectric strength and a sufficiently high dielectric constant to develop capacitance required by the system. It is important in the construction of the missile to maintain a relatively high resistance between the nose and tail sections. In other words. leakage must be reduced to a low level. If the resistance of the leakage path R is much greater than the resistance 8, it will necessarily follow that the RC time constant of the fuze circuit will be much less than that of the leakage path. As a result, electrical discharge through the detonator circuit is assured before significant dissipation of the charge occurs through the leakage path.

Because of the intense heating to which missiles may be subjected during re-entry into the earths atmosphere, they may be made from ceramic or other nonconducting materials. FIG. 2 shows a missile in which the nose and tail sections and 21 are made from quartz. Between the nose and tail is an intervening section 22 of dielectric material. This may also be made from quartz or any other dielectric suitable for the contemplated environment.

The nose section is lined with metal as indicated at 23, the metal being directly connected to a capacitor plate 24. Another capacitor plate 25 is connected to a metal liner 26 within the tail section. lnterconnecting the capacitor plates 24 and 25 is a fuzing circuit, including an ignition bead and a detonator such as described with reference to FIG. 1. For this reason, the details of the detonator circuit will not be described again.

During passage through. the atmosphere, the missile of FIG. 2 will become electrostatically charged as described with reference to FIG. 1. It is well known that the potential inside of a charged hollow body is everywhere constant and equal to that of the charge on the external surface of the body. Accordingly, the metal liners and associated capacitor plates are charged to a high potential as a result of the electrostatic phenome non affecting the exterior of the missile.

At the time of impact, the accumulated external surface charges near the area of impact on the nose are immediately discharged t) ground. It follows that the charge on the inner liner of the nose falls to target potential, and a significant potential difference is established between the capacitor plates 24 and 25 causing flow of current through the detonator circuit. This triggers the detonator and the warhead as has already been described.

In conclusion, it is pointed out that a fuze of the present type will not be adversely effected by passing through charged regions, such as charged cloud formations. Any such equi-potential field will affect both the nose and tail sections simultaneously and will not serve to establish a potential difference across the detonator circuit sufficient to trigger the detonator. Since no ionization effects are required, as in thyratron control circuits, the device is insensitive to cosmic rays and no shielding of components is required. The absence of electronic systems subject to countermeasure interference will also be noted.

In view of the substantial energy that is made available through use of the present invention, relatively insensitive detonators, requiring large energy dissipation for detonation, may be used. The inherent insensitivity of such a detonator to mechanical shock makes it highly desirable from a safety and countermeasure standpoint.

It should be emphasized that the novel fuzing system of this invention does not require an external source of electrical energy but develops its own source during flight. This makes for simplicity. economy, reliability, and light weight.

The various features and advantages of the invention are thought to be clear from the foregoing description. Others not specifically enumerated will undoubtedly occur to those skilled in the art, as will variations of the embodiments illustrated, all of which may be achieved without departing from the spirit and scope of the invention.

I claim:

1. In a missile the combination comprising:

a. a hollow metallic nose section and a hollow metallic tail section, said sections being concentric about the longitudinal axis of the missile for storing electrostatic energy generated by the passage of the missile through the atmosphere;

b. a dielectric section separating and electrically insulating said nose and tail sections one from another;

c. oppositely disposed first and second electrically conductive plates electrically insulated one from another and electrically connected to respectively said nose section and said tail section; and

d. a substantially noninductive electrical detonator circuit capable of withstanding voltages of about 5,000 volts including electrically activated detonating means connected between said first and second plates whereby said nose section first making electrical connection with a target at impact discharges its associated charge to the target and a potential difference is thereby established across said detonator circuit.

2. In a missile the combination comprising:

a. a hollow metallic nose section and a hollow metallic tail section said sections being concentric about the longitudinal axis of the missile for storing electrostatic energy generated by the passage of the missile through the atmosphere;

b. a dielectric section separating and electrically insulating said nose and tail sections one from another;

c. electrical charge storage means having first and second portions connected to respectively said nose and tail sections; and

d. a substantially noninductive electrical detonator circuit capable of withstanding voltage of about 5 ,000 volts including electrically activated detonating means connected between said first and second portions whereby said nose section first making electrical connection with a target at impact discharges its associated charge to the target and a potential difference is thereby established across said detonator circuit.

3. Apparatus as defined in claim 2 wherein said nose and tall sections comprise exterior wall portions of the missile. 

1. In a missile the combination comprising: a. a hollow metallic nose section and a hollow metallic tail section, said sections being concentric about the longitudinal axis of the missile for storing electrostatic energy generated by the passage of the missile through the atmosphere; b. a dielectric section separating and electrically insulating said nose and tail sections one from another; c. oppositely disposed first and second electrically conductive plates electrically insulated one from another and electrically connected to respectively said nose section and said tail section; and d. a substantially noninductive electrical detonator circuit capable of withstanding voltages of about 5,000 volts including electrically activated detonating means connected between said first and second plates whereby said nose section first making electrical connectioN with a target at impact discharges its associated charge to the target and a potential difference is thereby established across said detonator circuit.
 2. In a missile the combination comprising: a. a hollow metallic nose section and a hollow metallic tail section said sections being concentric about the longitudinal axis of the missile for storing electrostatic energy generated by the passage of the missile through the atmosphere; b. a dielectric section separating and electrically insulating said nose and tail sections one from another; c. electrical charge storage means having first and second portions connected to respectively said nose and tail sections; and d. a substantially noninductive electrical detonator circuit capable of withstanding voltage of about 5,000 volts including electrically activated detonating means connected between said first and second portions whereby said nose section first making electrical connection with a target at impact discharges its associated charge to the target and a potential difference is thereby established across said detonator circuit.
 3. Apparatus as defined in claim 2 wherein said nose and tall sections comprise exterior wall portions of the missile. 